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Question
How is root hair adapted for the absorption of water from the soil?
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Solution
The main root with its many branches form a network in the soil. The root hairs get entangled in the soil particles and remain in close contact with the capillary water surrounding the soil particles. The epidermal cells of root hairs have vacuoles which contain cell sap. Generally, the cell sap is more concentrated than the soil solution. As a result the water enters inside the root hair cells by endosmosis. This water dilutes the epidermal cell sap solution. Then water enters into the cortical cells by osmosis and reaches the endodermal cells and then pericycle cells. From this layer water then enters in the xylem tissue. In this way, the water is absorbed and translocated up to xylem of the root by osmosis.
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RELATED QUESTIONS
The figure given below is a diagrammatic representation of a part of the cross section of the root in the root hair zone. Study the same and then answer the questions that follow
(i) Name the parts indicated by the guidelines 1 to 4.
(ii) Which is the process that enables the passage of water from the soil into the root hair?
(iii) Name the pressure that is responsible for the movement of water in the direction indicated by the arrows. Define it.
(iv) Due to an excess of this pressure sometimes drops of water are found along the leaf margins of some plants especially in the early mornings. What is the phenomenon called?
(v) Draw a well labelled diagram of the root hair cell as it would appear if an excess of fertiliser is added to the soil close to it.
Draw a magnified view of the root-hair, and describe, how it helps in the absorption of water from the soil.
The alongside diagram A shows a root hair growing through the soil particles. Diagram B is the root hair of an aquatic plant.
(i) Name the parts 1,2,3.
(ii) Name two substances which enter the root hair. What are their uses?
(iii) By what process do these substances enter the root hair?
(iv) Account for the different shapes of root hairs in the two diagrams.
Name the following:
The solution outside the cell having lower solute concentration than the fluids.
Name the following:
Name the process by which intact plants lose water in the form of droplets.
In the zone of absorption, epidermal cells form unicellular hair-like extensions called ________.
____________plants like orchids absorb water vapours from air with the help of epiphytic roots having special tissue called velamen.
Epiphytic plants like ____________ absorb water vapours from air with the help of epiphytic roots having special tissue called velamen.
Name the following:
Unicellular outgrowths from the epidermis of roots.
